Apologies if it sounds like creepy greentext shitposting. In a more eloquent/straightforward way the profit motive for anime has shifted towards multi approach consumer markets (i.e. merch shit) and has moved towards immediate returns via target audiences that consume said merch which is largely males with lots of disposable income. Harem style isekais (though there some good subversions out there on it for every 10 creepy harem ones) are made not just to fulfill weird pervy fetishes but also because it allows a large cast of characters to be marketed and consumed (all the anime figure dolls, anime body pillows, etc). It also falls into an area of self wish fulfillment versus how other anime deep dive into far deeper and introspective materials (Ergo Proxy, Perfect Blue, Grave of the Fireflies, etc). Anime can be arthouse, but like western media many companies also want to sell slop (and some of that slop is pretty perverted slop). Sorry if my previous comment came off weird, comrade.